1. Field of the Invention
This invention relates to an abrasive member, such as an abrasive sheet or an abrasive disk, for use in finish polishing for abrading an end of an optical connector ferrule having a ferrule hole, in which an optical fiber has been inserted and secured, into a convex spherical surface having very high return loss characteristics.
2. Description of the Prior Art
As techniques for abrading an end of an optical connector ferrule having a ferrule hole, in which an optical fiber has been inserted and secured, into a convex spherical surface, various polishing methods utilizing abrasive sheets or free abrasive grain retaining films have heretofore been proposed.
One example of the polishing methods is proposed in Japanese Unexamined Patent Publication No. 3(1991)-81708. With the proposed polishing method, a predetermined level of tension is imparted to a cellulose type of resin film, and an end of an optical connector ferrule is pushed against the surface of the resin film and slid on the surface of the resin film. During the sliding movement of the end of the optical connector ferrule, a coolant liquid containing silica type of abrasive grains is supplied to the position, at which the end of the optical connector ferrule comes into contact with the surface of the resin film.
However, with the aforesaid polishing of the optical connector ferrule, it is not always possible to carry out the polishing such that the surface smoothness of the ferrule surface and the optical fiber surface may be kept high, such that a difference in level between the ferrule surface and the optical fiber surface may not occur, and such that the very high return loss characteristics may thereby be obtained.
In particular, there is a difference in abrasion characteristics between the ferrule, which is constituted of a ceramic material, and the optical fiber, which is constituted of a glass material, due to the difference in material. Also, the polishing is carried out while the abrasive member is being kept in the elastic state such that the end of the ferrule may be abraded into a convex spherical surface. For such reasons, it is difficult to abrade the end of the ferrule into a desired shape, and considerable time and labor are required to control the conditions for the polishing.